| 1. |
|
|
| 2. |
|
|
| 3. |
- Nguyen, T. N. A., et al.
(author)
-
Correlation of magnetic and magnetoresistive properties of nanoporous Co/Pd thin multilayers fabricated on anodized TiO2 templates
- 2020
-
In: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 10:1
-
Journal article (peer-reviewed)abstract
- In this study, we consider a technological approach to obtain a high perpendicular magnetic anisotropy of the Co/Pd multilayers deposited on nanoporous TiO2 templates of different types of surface morphology. It is found that the use of templates with homogeneous and smoothed surface relief, formed on silicon wafers, ensures conservation of perpendicular anisotropy of the deposited films inherent in the continuous multilayers. Also, their magnetic hardening with doubling of the coercive field is observed. However, inhomogeneous magnetic ordering is revealed in the porous films due to the occurrence of magnetically soft regions near the pore edges and/or inside the pores. Modeling of the field dependences of magnetization and electrical resistance indicates that coherent rotation is the dominant mechanism of magnetization reversal in the porous system instead of the domain-wall motion typical of the continuous multilayers, while their magnetoresistance is determined by electron-magnon scattering, similarly to the continuous counterpart. The preservation of spin waves in the porous films indicates a high uniformity of the magnetic ordering in the fabricated porous systems due to a sufficiently regular pores array introduced into the films, despite the existence of soft-magnetic regions. The results are promising for the design and fabrication of future spintronic devices.
|
|
| 4. |
- Wu, W. B., et al.
(author)
-
Complex magnetic ordering in nanoporous Co/Pd (5)-IrMn multilayers with perpendicular magnetic anisotropy and its impact on magnetization reversal and magnetoresistance
- 2020
-
In: Physical Chemistry Chemical Physics. - : Royal Society of Chemistry (RSC). - 1463-9076 .- 1463-9084. ; 22:6, s. 3661-3674
-
Journal article (peer-reviewed)abstract
- We have systematically investigated the magnetization reversal characteristics and magnetoresistance of continuous and nanoporous [Co/Pd](5)-IrMn multilayered thin films with perpendicular magnetic anisotropy at different temperatures (4-300 K). For their nanostructuring, porosity was induced by means of deposition onto templates of anodized titania with small (similar to 30 nm in diameter) homogeneously distributed pores. The magnetization reversal and magnetoresistance of the porous films were found to be closely related to the splitting of the ferromagnetic material into regions with different magnetic properties, in correlation with the complex morphology of the porous system. Independent magnetization reversal is detected for these regions, and is accompanied by its strong impact on the magnetic order in the capping IrMn layer. Electron-magnon scattering is found to be a dominant mechanism of magnetoresistance, determining its almost linear field dependence in a high magnetic field and contributing to its magnetoresistance behavior, similar to magnetization reversal, in a low magnetic field. Partial rotation of IrMn magnetic moments, consistent with the magnetization reversal of the ferromagnet, is proposed as an explanation for the two-state resistance behavior observed in switching between high-resistive and low-resistive values at the magnetization reversal of the porous system studied.
|
|
| 5. |
- Wu, W. B., et al.
(author)
-
Influence of interfacial magnetic ordering and field-cooling effect on perpendicular exchange bias and magnetoresistance in nanoporous IrMn/ Co/Pd films
- 2020
-
In: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 127:22
-
Journal article (peer-reviewed)abstract
- We have studied systematically the effect of field cooling on the magnetic properties of continuous and porous IrMn/[Co/Pd] films. It is found that the coexistence of two ferromagnetic (FM) phases in the porous film, namely, hard-magnetic and soft-magnetic ones, with significantly different magnetic properties relates to the role of pore edges and modifies its magnetic and magnetoresistive properties. It is shown that annealing of the films with their subsequent cooling in an external magnetic field applied for aligning the magnetic moments in the antiferromagnetic (AFM) IrMn layer improves effectively the uniaxial perpendicular anisotropy of the [Co/Pd] layer and induces unidirectional anisotropy in its hard-magnetic regions, blocking simultaneously the soft-magnetic parts by pinning their magnetic moments along the film plane. Magnetoresistance of both continuous and porous films is found to be determined mainly by electron-magnon scattering, whereas the complex morphology of the porous film providing different orientations of exchange coupling at the AFM/FM interface in different film regions modifies significantly the spin-dependent electron transport. The revealed asymmetry of the field dependences of magnetoresistance is attributed both to unidirectional magnetic anisotropy of the FM layer and its splitting into magnetically nonequivalent regions in the porous films. The origin of the observed phenomenon is associated with a local influence on the orientation of AFM magnetic moments by an adjacent ferromagnet.
|
|
